Sway restrictor bracket for a draft link of a three point hitch

ABSTRACT

The sway restrictor includes a bracket attachable between the draft link or arm and an adjacent upwardly and downwardly extending structural element of a work machine, and is operable for substantially restricting or preventing relative sideward movement therebetween, particularly swaying of the hitch, while allowing relative upward and downward movements thereof, including tilting movements.

This divisional application claims priority under 35 U.S.C. §120 fromU.S. patent application Ser. No. 11/217,631 filed on Aug. 31, 2005, nowU.S. Pat. No. 7,377,330 by Roger D. Mickelson et al. with the sametitle, the full disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a three point hitch for a work machinesuch as a tractor used for construction, earth moving, agriculture, andother purposes, and more particularly, to a sway restrictor including acompact bracket attachable between a draft link or arm and an adjacentupwardly and downwardly extending fixed structural element of a workmachine and operable for substantially restricting or preventingrelative sideward movement therebetween, particularly swaying of thehitch, while allowing relative upward and downward movements thereof,including tilting movements.

BACKGROUND ART

Work machines such as tractors often include three point hitches forsupporting and towing tools and implements, such as scrapers, blades,sprayers, and the like. For many applications, it is required or desiredto have the ability for the towed tool or implement to closely follow adesired or predetermined path, such as an edge or boundary of an area tobe scraped, for instance, the edge of a soil area next to a foundation,and where exceeding the boundary is undesirable or can possibly causedamage such as that which could result from contact between a scraper orblade and a foundation or wall. However, such three point hitchestypically utilize draft links or arms for supporting and connecting tothe lower portions of a tool or implement. The vertical position of thedraft links is typically individually precisely controllable using fluidcylinders connected between the draft links and the work machine, butthe connections allow generally free relative side to side movements ofthe draft links and the work machine over a relatively large amount oftravel. Some sideward movement is required for hitches for constructionand landscaping applications wherein the draft links are individuallyvertically movable by separate cylinders, so as to effect and facilitatesideward tilting of a scraper or blade. However, such side to sidefreedom of movement permitted by known hitches also allows swaying ofthe tool or implement and a resultant difficulty in maintaining preciseside to side positioning thereof, for instance, for alignment with anedge or boundary of an area being worked by the tool or implement, suchas soil area being landscaped adjacent to a foundation or wall.

To substantially limit or prevent such swaying, it is known to provideblocks which may be mounted in one or more alternative orientations orpositions on a work machine or draft link, for preventing sway in onedirection only. Such blocks are advantageous as they are relativelycompact and allow close spacing between a wheel of a tractor and a draftlink, but a disadvantage is that the blocks are required to be used inassociation with both of the draft links to prevent swaying in bothsideward directions. Reference in this regard, Slosiarek et al. U.S.Pat. No. 3,847,228, issued Nov. 12, 1974 to Allis-Chalmers ManufacturingCompany; and Teich U.S. Pat. No. 4,640,522, issued Feb. 3, 1987 to Deere& Company. As another disadvantage, a problem that can arise when usingsuch blocks with a sidewardly tiltable hitch is that at least one of thedraft links would have to be allowed to move sidewardly to accommodatesideward tilting movement, which would also allow at least some of thesideward swaying not desired for the reasons discussed above.

As an alternative, a variety of single arms and struts have beendeveloped for connection between a structural element of a work machineand one of the draft links of a three point hitch, to providebi-directional limitation of movements of the draft link, to therebyattempt to eliminate the need for devices such as blocks in associationwith each of the draft links. Reference in this regard, Kunze U.S. Pat.No. 4,203,613, issued May 20, 1980 to Jean Walterscheid GmbH; and LangU.S. Pat. No. 4,265,464, issued May 5, 1981 to Deere & Company. However,devices such as these suffer from shortcomings including requirementsfor multiple pivotal connections, complexity, large size and spacerequirement, and relatively high cost.

Thus, what is sought is a sway restricting apparatus which facilitatessideward tilting of a hitch, and overcomes one or more of the problemsand/or disadvantages set forth above.

SUMMARY OF THE INVENTION

What is disclosed is a sway restrictor for a draft link of a three pointhitch for a work machine such as a tractor, which overcomes one or moreof the problems and/or disadvantages set forth above.

According to a preferred aspect of the invention, the sway restrictorincludes a generally C-shaped bracket having a first leg portion and asecond leg portion spaced from the first leg portion and defining aspace therebetween adapted for cooperatively receiving an upwardly anddownwardly extending structural element of a work machine therein. Thebracket is preferably of cast or forged metal, heavy duty construction.The structural element can include, for instance, but is not limited to,a generally vertically extending fixed edge or lip of a structuralmember such as a frame member, transmission housing or axle housing, andalso should be of strong construction. The three point hitch can belocated on a rear end, or a front end, of a work machine, and the edgeor lip will preferably face the same direction as the draft links of thehitch. With the structural element received in the space of the bracket,an inner surface of the first leg portion of the bracket will face afirst side of the structural element, and an inner surface of the secondleg portion will face a second side of the structural element oppositethe first side. One of the leg portions preferably has a passage orcavity therein extending in a sideward or transverse direction generallytoward the other of the leg portions, so as to be in connection with thespace. The sway restrictor includes at least one mounting elementadapted for mounting the bracket on a draft link of a three point hitchmounted on a work machine such that the selected upwardly and downwardlyextending structural element thereof will be cooperatively received inthe space. The restrictor includes at least one wear pad disposed in thepassage in connection with the space, so as to be extendible into thespace, and an adjusting element adjustably movable in cooperation withthe wear pad for adjustably holding the wear pad in a position extendinginto the space, for restricting relative transverse movement of thedraft link and the structural element cooperatively received in thespace.

According to another preferred aspect of the preferred invention, theadjusting element can be adjustably moved to position the wear pad inabutting contact with the adjacent side of a structural element, suchthat the inner surface of the other leg portion of the bracket abuts anopposite side of the structural element, to thereby limit or effectivelyprevent transverse sway of the draft link as well as other portions ofthe three point hitch, even under high loading conditions such asexperienced while using a soil scraper or blade, while still allowingrelative vertical movements of the hitch and work machine.

As a result, undesired transverse or side sway or movements of a tool orimplement towed by the work machine using the hitch can be substantiallyeliminated or reduced to a desired or required extent, therebyfacilitating the ability of the tool or implement to closely follow apredetermined path, such as an edge or boundary of a soil area beinglandscaped located next to a foundation or wall.

According to another preferred aspect of the invention, the bracket ismountable on a draft link using suitable conventional fasteners, such asbolts or the like, and the adjusting element includes a threaded memberthreadedly engaged with the bracket or draft link in a position forbearing against the adjustable wear pad.

According to another preferred aspect of the invention, an inner surfaceof the leg includes a second wear pad, and one or both of the oppositesides of the structural element include wear pads, respectively,positioned so as to extend along a path of upward and downward movementof the draft link, for abutting the wear pad or pads on the bracket andproviding oppositely facing surfaces over which they can travel orslide.

As an advantage of the bracket of the invention, setup and adjustmenttime are greatly reduced. Complexity and size of the apparatus forrestricting sway are both also substantially reduced. As a result, thebracket has utility for use on small and compact classes of tractors andother work machines, and on larger tractors where the tires are spacedclose together. As another advantage, the adjusting element can beeasily and conveniently positioned for providing a desired amount ofallowed sway, including essentially no sway, as desired or required fora particular application. The adjustability of the wear pad also allowscompensating for wear as it occurs, such that a desired amount ofpermissible sway, or no substantial sway, can be maintained for asubstantial period of time without requiring replacement of parts andthe like.

As a still further important advantage, the restrictor prevents sidewardswaying of the hitch, while still allowing the other of the draft linksto move sidewardly, for facilitating independent upward and downwardmovements of the draft links necessary for sideward tilting movements ofa tool or implement mounted on the hitch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view of a rear end of a work machinerepresentative of a tractor used for construction purposes, including athree point hitch and a sway restrictor of the invention installedthereon, and showing partially in dotted lines, a conventional soilscraper used for landscaping and the like, mounted on the hitch;

FIG. 2 is an enlarged fragmentary perspective view of a draft link ofthe three point hitch and sway restrictor of FIG. 1, showing astructural element of the work machine received in a bracket of the swayrestrictor;

FIG. 3 is another enlarged fragmentary perspective view of the draftlink and sway restrictor in association with the structural element;

FIG. 4 is a sectional representation of the sway restrictor mounted onthe draft link and engaged with the structural element of the workmachine, illustrating internal aspects of the restrictor;

FIG. 5 is a simplified schematic rear view of the hitch and restrictor,with the hitch in a horizontal, non-tilted orientation; and

FIG. 6 is another simplified schematic rear view of the hitch andrestrictor, with the hitch tilted, to show an advantage of therestrictor.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, in FIG. 1, a rear end of a conventionalwork machine 10 is shown, work machine 10 being intended to berepresentative of a wide variety of work machines such as a tractor,used for purposes such as construction, landscaping, agriculture, andthe like. Work machine 12 includes a rear frame 12, which can be aweldment, casting or other member or structure of heavy-dutyconstruction, including at least one and possibly a pair of spaced apartstructural elements 14 and 16, comprising upwardly and downwardlyextending side plates including generally arcuate, upwardly anddownwardly extending rear edge portions 18 and 20, respectively.Structural elements 14 and 16 support a three point hitch 22, which, inturn, is capable of supporting any of a wide variety of tools andimplements, such as a soil scraper 24 shown. Essentially, in operation,scraper 24 is supported on three point hitch 22 at a desired elevationin relation to the soil, and pulled or towed in a forward direction,denoted here generally by arrow A, for scraping and holding soil forlater deposition on the ground. Scrapers, such as scraper 24, arecommonly used in landscaping and other construction applications forleveling soil next to structures, such as walls, foundations, and thelike, wherein it is desirable to tow the scraper as close as possible tothe wall or foundation for working the soil in that area. A scraper suchas scraper 24 may also be forwardly or rearwardly tilted for more orless aggressive scraping action, and may be sidewardly tilted to enableforming the sides of ditches, swails, and the like.

Three point hitch 22 generally includes a pair of draft links, includinga first draft link 26 and a second draft link 28. Each of the draftlinks 26 and 28 includes a mounting end portion 30 which is mounted to,or adjacent to, one of the structural elements of rear frame 12, forpivotal upward and downward movement of a free end 34 thereof, asillustrated by pivotal mounting of mounting end portion 30 of firstdraft link 26 to structural element 14 by pivot pin 32. A tool orimplement, here represented by soil scraper 24, is attached to free endportions 34 of draft links 26 and 28, by pins 36 which extend throughholes through free end portions 34 and devises 38 on scraper 24. Freeend portion 34 of first draft link 26 is pivotally connected to a lowerend of a first tilt cylinder 40, the upper end of cylinder 40 beingpivotally connected to one end of a rocker shaft 42. Similarly, free endportion 34 of second draft link 28 is connected to a second tiltcylinder 44 which is also connected to rocker shaft 42. First and secondtilt cylinders 40 and 44 are individually extendible for adjusting avertical pivotal position of the respective free end portions 34, foreffecting sideward tilting of the hitch and a tool or implementconnected thereto such as scraper 24. Rock shaft 42, in turn, ispivotally connected by pins 46 and 48 to structural elements 14 and 16,respectively, so as to be vertically pivotable in relation thereto, ascontrolled by a main lift cylinder 50, for adjusting an overall verticalheight or elevation of a tool or implement mounted on three point hitch22, such as soil scraper 24, as desired or required for a particularapplication. A centrally located center link of the hitch also connectsto a center portion of a tool or implement, and is movable by anothercylinder to effect forward and rearward tilting of the tool orimplement. Also, as an alternative it should be understood that hitch 22may be equipped with only one tilt cylinder for effecting sidewardtilting movements.

Here, referring also to FIG. 6, it should be understood that when freeend portions 34 of draft links 26 and 28 are connected to a tool orimplement, such as scraper 24, the sideward spacing between free endportions 34 of the draft links 26 and 28 is substantially fixed, orvariable only by a small amount. As a result, when draft links 24 and 26are positioned at different heights for effecting tilting of a tool orimplement, at least one of the draft links must be allowed to movesidewardly relative to the adjacent structural element. This isillustrated by arcuate line 52 in FIG. 6. However, for manyapplications, for instance, when scraping soil next to a wall orfoundation, it is desirable to have the capability for preventing anysubstantial or significant side-to-side movement or swaying of a scrapersuch as scraper 24, such that the wall or foundation is notinadvertently contacted or impacted so as to possibly damage the scraperand/or wall or foundation, and such that areas closely adjacent to thewall or foundation are not missed during the scraping operation or path.It is also desirable that any apparatus that provides such capability ofpreventing or substantially restricting swaying movements of a tool orimplement, such as scraper 24, allow the required movement of at leastone of the draft links 26 and 28, to allow effecting sideward tiltingthereof, without subjecting components of the hitch, work machine,and/or tool or implement, to undue stress or wear. Still further, it isalso desirable for any such apparatus to be strong and durable, yetcompact and simple in construction.

Referring also to FIGS. 2, 3 and 4, a sway restrictor 54 constructed andoperable according to the teachings of the invention, is shown mountedon free end portion 34 of first draft link 26, adjacent to rear edgeportion 18 of structural element 14, so as to be capable of movingupwardly and downwardly in relation thereto with the upward and downwardmovements of free end portion 34 of draft link 26. Sway restrictor 54preferably includes a generally C-shaped bracket 56 of suitable heavyduty construction, such as of cast or forged metal. Bracket 56 has afirst leg portion 58, and a second leg portion 60 spaced sidewardly fromleg portion 58, defining a space 62 therebetween. In this way, bracket56 extends or wraps partially around rear edge portion 18 of structuralelement 14, for limiting the amount of side-to-side relative movementtherebetween denoted by arrow B in FIG. 4. Such side-to-side movement Bwill be generally about perpendicular to the forward direction, asdenoted by arrow A in FIG. 1. With rear edge portion 18 of structuralelement 14 cooperatively received in space 62, an inner surface 64 offirst leg portion 58 will face an outer or first side 66 of structuralelement 14, and an inner surface 68 of second leg portion 60 will facean opposite second side 70 of structural element 14. As a result,relative side-to-side movements of draft link 16 and structural element14 will be limited to the amount, if any, that the sideward extent ofspace 62 is larger than the sideward extent of structural element 14between sides 66 and 70 thereof. To provide an ability to vary andsubstantially limit relative sideward movement of structural element 14and draft link 26, and also to increase the durability of swayrestrictor 54, at least one of leg portions 58 and 60, and preferablyboth, include a wear pad positioned to bear against the adjacent side ofstructural element 14, as illustrated by wear pads 72 and 74 in FIG. 4.Wear pad 72 of first leg portion 58 is preferably located in asidewardly extending passage 76 in and preferably through leg portion58, so as to extend into space 62 in a position to bear against firstside 66 of structural element 14. Similarly, wear pad 74 is disposed ina cavity 78 in inner surface 68 of second leg portion 60 and extendssidewardly into space 62 to bear against second side 70 of structuralelement 14. As an additional wear reducing feature, sides 66 and 70 ofstructural element 14 preferably include elongate, arcuate shape wearplates 80 and 82 thereon, respectively, positioned for contact with wearpads 72 and 74, respectively, along the extent of vertical travel ofdraft link 26 relative to structural element 14.

Also preferably, an adjusting element 84 is provided for adjusting asideward position or amount of extension of wear pad 72 into space 62.Adjusting element 84 preferably comprises a threaded member threadedlyreceived in a threaded hole 86 through draft link 26, and bears againsta backing plate 88 disposed between wear pad 72 and adjusting element84. A locking nut 90 is threadedly engaged with adjusting element 84 andcan be brought to bear against draft link 26 for holding adjustingelement 84 and wear pad 72 in a desired position. Here, referringparticularly to FIG. 4, it can be observed that virtually no space orgap exists between wear pad 72 and plate 80, and wear pad 74 and plate82, such that little or no sideward swaying of draft link 26 will beallowed, while vertical relative movement through the anticipated rangeof vertical positions of draft link 26 will be allowed, as generallyillustrated in FIG. 1 by the upward extent of wear plate 80 above draftlink 26. Suitable materials of construction of wear pads 72 and 74 caninclude, but are not limited to, well known, commercially availableglass filled plastics, lubricant impregnated metallic materials, andsintered materials, it being recognized that other materials, such aslow friction ceramics, and the like, can also be used. Plates 80 and 82are preferably constructed of steel.

Sway restrictor 54 is suitably mounted in connection with draft link 26,here, by a pair of bolts 92 which pass through holes 94 through draftlink 26 and are threadedly received in threaded holes 96 in first legportion 58 of bracket 56. Other means of attachment, including bywelding, and also other methods, such as casting or otherwise forming inplace, and the like, can also be used.

Turning also to FIGS. 5 and 6, in FIG. 5, draft links 26 and 28 of threepoint hitch 22 are shown in a generally horizontal configuration besidestructural elements 14 and 16, respectively. In this view, it can beobserved that the centers of each of draft links 26 and 28 are located adistance X from a center line of the work machine on which the hitch ismounted. Distance X is shown here also being equal to a distance Zbetween centers of the draft links at their points of attachment to thescraper or other implement or tool, as held constant by such attachment.Sway restrictor 54 of the invention is shown mounted on draft link 26and in cooperative engagement with structural element 14. In FIG. 6,hitch 22 is shown sidewardly tilted such that draft link 28 has beenlowered below draft link 26. It can be observed here that swayrestrictor 54 has maintained draft link 26 at distance X from the centerline, whereas lowered draft link 28 has followed an arcuate line 52 soas to now be a distance X-n from the center line. Distance Z remainsconstant. As a result, it should be apparent that using sway restrictor54, draft link 26 is able to move upwardly and downwardly along astraight line to thereby prevent any substantial sideward swayingthereof, and also of a tool or implement such as scraper 24 (FIG. 1)mounted thereon, while draft link 28 is permitted to move sidewardly asrequired to accommodate tilting movements such as that illustrated inFIG. 6.

Here, it should be appreciated that such sway restricting capabilitiesare accomplished with a sway restrictor illustrated by restrictor 54,which is of robust, strong construction, yet which is relatively compactand simple, particularly to set up and adjust. Additionally, it shouldbe appreciated that a sway restrictor of the invention, such as swayrestrictor 54, can be utilized with a draft link on either side of athree point hitch, and has utility for hitches located on both the frontand rear of a work machine such as a tractor or the like. Still further,adjustments, for instance, to compensate for wear of the wear pads, orfor setting a desired amount of permitted sway, are easily and simplyaccomplished, utilizing adjusting element 84.

It will be understood that changes in the details, materials, steps, andarrangements of parts which have been described and illustrated toexplain the nature of the invention will occur to and may be made bythose skilled in the art upon a reading of this disclosure within theprinciples and scope of the invention. The foregoing descriptionillustrates the preferred embodiment of the invention; however,concepts, as based upon the description, may be employed in otherembodiments without departing from the scope of the invention.Accordingly, the following claims are intended to protect the inventionbroadly as well as in the specific form shown.

1. A sway restrictor connected to a draft link of a three point hitch,comprising: a generally C shaped bracket having a first leg portion anda second leg portion spaced from the first leg portion, the leg portionsdefining a space therebetween adapted for cooperatively receiving anupwardly and downwardly extending structural element of a work machinetherein such that an inner surface of the first leg portion faces afirst side of the structural element and an inner surface of the secondleg portion faces a second side of the structural element opposite thefirst side, at least the first of the leg portions having a passagetherein extending in a transverse direction generally toward the otherof the leg portions and in connection with the space; at least onemounting element mounted on the draft link of the three point hitchmounted on a work machine such that the structural element thereof willbe cooperatively received in the space and the first leg portionconfigured for receiving the mounting element; a wear pad disposed inthe passage so as to be extendible in the transverse direction into thespace out of the passage and at least a portion of the wearpad isretractable into the passage by an adjustable element; and the adjustingelement coupled to the first leg portion and disposed in connection withthe wear pad and adjustably movable in cooperation with the wear pad foradjustably holding the wear pad in a position extending from within thepassage into the space, for restricting relative transverse movement ofthe draft link and the structural element cooperatively received in thespace; and the first leg portion is connected to the draft link and theadjusting element is threadedly mounted in a threaded hole through thedraft link and is threadedly movably inwardly and outwardly in relationthereto for adjustably moving the wear pad.
 2. The sway restrictor ofclaim 1, wherein the other of the leg portions includes a wear padmounted partially within a second passage on the inner surface thereofpositioned to abut the second side of the structural element.
 3. Thesway restrictor of claim 1 wherein the C shaped bracket is configured toreceive a portion of the structural element having a wear plate on atleast one of the sides of the structural element.
 4. The sway restrictorof claim 3, wherein the C-shaped bracket is configured to receive aportion of the structural element having wear pads on each of the sidesof the structural element.
 5. The sway restrictor of claim 1, whereinthe mounting element is mounted on a flat surface of the draft link, andthe adjusting element is connected to a back plate that is restricted totravel within the passage, the back plate positioned to bear against thewear pad.